1. Field of the Invention
The present invention relates to cationic vitamin E derivatives and uses thereof, and more particularly, to quaternary nitrogen-containing vitamin E or polyethoxylated vitamin E, which shows a high substantivity to hair or skin and a high dispersibility in water as well as may be advantageously employed as a surface active agent in cosmetics or medicines, and to uses thereof.
2. Description of the Prior Art
Vitamin E is the generic name of a mixture of lipid soluble phenols, tocopherols: and tocotrienols possessing general structural features an aromatic chromanol head and a 16-carbon hydrocarbon tail. The number of methyl substituents in the chromanol nucleus gives rise to .alpha., .beta., .tau., .delta. isomers, whereas the saturation of the hydrocarbon chain differentiates tocopherols with a saturated chain from tocotrienols with an unsaturated chain as forms of vitamin E.
Vitamin E is widely employed as an active anti-oxidation agent in drugs, foods and cosmetics. And, vitamin E is known to be useful in healing injuries and protecting the skin against the ultraviolet irradiation as well as be useful as an anti-inflammation agent.
Vitamin E is a viscous brown liquid which is soluble in oils and not soluble in water. It is considerably resistant against the heat, strong acids and visible light in the absence of oxygen species. It is, however, sensitive to the ultraviolet light, alkalis and oxygen species.
Many attempts have been made to improve the stability of vitamin E against oxidation by oxygen species. For example, lipophilic tocopherol derivatives and hydrophilic tocopherol derivatives were proposed.
Lipophilic tocopherol derivatives may include, for example, tocopheryl esters such as tocopheryl acetates, tocopheryl linolates and tocopheryl nicotinates. Tocopheryl acetates may be obtained by esterifying the tocopherols with acetic acid and are most widely employed in various fields due to their improved stability against oxidation. Tocopheryl linolates are an ester of tocopherol with linoleic acid and show an improved stability against oxidation and an improved substantivity to skin. They are recently advantageously employed in cosmetics. Tocopheryl nicotinates, which are disclosed in Japanese Patent Publication Sho 55-2431, may be obtained by reacting 1-alkyl-2-halopyridinium with nicotinic acid in the presence of a tertiary amine to give nicotinoyloxy pyridinium, which is then subjected to reaction with tocopherol in the presence of a tertiary amine. Japanese Patent Publication Sho 55-2431 teaches that the tocopheryl nicotinates exhibit capillary vasodilating and toxiciding abilities and an activity for lowering cholesterol level in blood stream and that the tocopheryl nicotinates are found to be an excellent slow-releasing drug.
Because solubility or dispersiblity in water of the liphophilic tocopherols is poor, several attempts have been made to improve these properties and, as a result, tocopherols with an improved hydrophilicity were proposed.
One example of such tocopherols with an improved hydrophilicity is d-.alpha.-tocopherylglycol 1000 succinate [The Condensed Chem. Dictionary, 1981, VAN NOSTRAND], which is an ester of tocopherol with ethoxylated succinic acid and represents the vitamin E having a good water dispersibility. This compound is employed as a food additive and used as a surfactant in cosmetics and drugs.
Another example of hydrophilic vitamin E is a polyethoxylated vitamin E which is developed by me and other colleagues and is disclosed in U.S. Ser. No. 07/857,652, now U.S. Pat. No. 5,235,073. The polyethoxylated vitamin E has an emulsifying, dispersing and solubilizing abilities and may be advantageously employed as a surface active agent in cosmetics and drugs.
Another hydrophilic vitamin E is a quaternary nitrogen-containing tocopheryl nicotinate which may be advantageously formulated into various drugs due to its physiological activities and good solubility in water or aqueous solvents. However, the above compound is quaternized at nicotinic acid moiety, not at tocopherol moiety.
Besides, the present inventor has a conception that catanionic physiologically active materials can efficiently exhibit their activity when applied to the skin or hair due to their good substantivity to the skin or hair and can exhibit good moisture retention effect due to their solubility in water or aqueous medium, and has made extensive studies to provide vitamin E derivatives exhibiting an improved substantivity to hair or skin, a high dispersiblity in water and an excellent surface activity while retaining the physiological activities of vitamin E species. As a result thereof, I accomplished the present invention.